Welding machine



Apri1s,1941. EMDARNER f 2237551 45 eeeeeeeeee tl April s, 1941.

F. M. DARNER' wnmme uAcHINE Filed uar'ch 21, 1939 4 Sheets-Sheet 2 mum- IN VENT OR. 772525276 M .DA P/Vfi? BY M AIToRNEYs April 8, 1941.. F M DARNR 2231551 WELDING MACHINl M oRNEY.

April 8, 1941. F, M DARNER 2237551 WELDING HACHINE Filed Marchl 21, 1939 4 Sheets-Sheet 4 A .6. suPP r INVNTOR,

L J F/PEflHa/c MlwfwE/P i' .a BY M ATTORNEYS Patented Apr. 8, 1941 WELDING MACHINE Frederic M. Darner, Shaker Heights, Ohio, as-

signor, by meane assig'nments, to Republic Steel Corporation, Cleveland, Ohio, a corporation of New Jersey Application March 21, 1939, Serial No. 263,15!-

8 Clalms. (CI. 219 -6) This Iinventlon relates to the art of electric welding and more particularly to apparatus for welding tubing or pipe by the electric resistance method.

In the manufacture of electric welded tubing a metallic strip is formed into a tubular blank having abutting edge surfaces which are subscquently welded together as the blank passes through the welding throat of a welding machine. At the welding throat the edges of the tubing are urged together by devices such as pressure or welding rolls engaging opposite sldes of the tube and the welding current may be supplied to the tubular blank by electrode rolls engaging the blank on either side of the seam. In order consistently to produce high quality tubing by such a method and apparatus it is desirable to correlate and maintain substantially constant the three principal factors determining the character of the weld, namely, the speed of the blank, the intensity of the current and the pressures exerted on the tube at the welding throat.

Heretoiore it has been customary to employ various controlling devices and indicating mechanisms in conjunction with welding inachines in order to maintain the speed of travel of the blank and the fiow of welding current at the desired values. However so far as I am aware no one has provided a welding machine wherein the pressures exerted on the blank may be readily determined. It is therefore an object `of my invention to provide a welding apparatus ing the pressures exerted by the welding rolls urging the edges of the seam together and the pressures exerted by the electrodes against the blank. Another object is to provide an appa.. ratus which will instantaneously show any variations in welding pressures which may occur during the Operation of the machine. A further object is to provide a sturdy` and eilicient apparatus which will accurately indicate the weldmg pressures. v i

V ther objects and advantages of the invention will become apparent from' the following description of a preferred form thereof'taken in conjunction with. the accompanying drawings wherein:

Figure 1 is an end elevation of a welding machine embodying my invention; Figure 2 is an end view, partially in section, on an enlarged scale, showing the welding throat of the machine illustrated in Figure 1 and including the welding or pressure rolls and a portion of the electrode rolls; Figure 3 is a plan view of the apparatus shown in Figure 2 with parts broken away and the electrode rolls removed for convenience of illustration; -Figure 4 is an elevational view partly in section showingvthe apparatus illustrated in Figure 3; Figure 5 is an enlarged sectional view taken along the line 5-5 of Figure 2; Figure 6 is a sectional illustration of a preferred lform of pressure responsive device utilized to measure thepressures exerted in the apparatus; Figure 7 is a sectional view of the pressure responsive device as indicated by the line 1-1 on Figure 6; and Figure 8 is a wirlng diagram iliustrating a preferred form of the electrical circuit used in conjunction with the pressure responsive device shown in Fgures 6 and 7 to indicate the welding pressures.

As shown in Figure 1 of the drawings a preferred form of welding machine embodying my invention maycomprise a suitable base or frame I0 having mounted thereon a carrlage II on which the pressure or welding rolls 12 and H are adjustably mounted. The rolls I2 and lll engage opposite sides of the tubular blank A and urge the edges thereof together, the position of the rolls being adjustable by mechanism to be described below so that the pressure exerted on the blank can be varied by the rolls. According to my invention this pressure is preferably transmitted through and measured by' the pressure responsive device I5, variations in the pressure being indicated by the gage or meter I`I which may be mounted at any convenient location, for example, on the upright frame member I8.

The welding current is supplied to the tube through electrode rolls is and 29 engaging opposite sides of the seam of the blank A. The electrode rolls may be carried by suitable bearings in bracket 28 which in turn is mounted for vertical sdjustment by means of the screw mecha- .njsin 22 on the uprlght frame member 98. The pressures exerted by the electrodes on the tube lmay' be adjusted by vertical adjustment of the electrode rolls and are preferably Vmeasured by a pressure responsive deviee similar in all material respects to the pressure rfipensive devlce I5 and positioned to measure the downward thrust exerted on the welding rolls I2 and I4 by the tube blank A, which thrust isdue to the pressurel exerted by the electrode rolls against the blank. The pressure changes as measured by the pressure responsive device 25 preferably are indicated by the gage or meter 21l mounted adjacent meter I1.. If desired one'or both gages or meters may include recording mechanism.

To provide for adiustment of the welding rolls I2 and I4 and also to provide means for indicating the pressure which the rolls exert on the tube, the rolls are preferably mounted as shown in Figures 2 to 5 for rotation on vertical shafts 28 and 29, respectively, which in tum are carried by slides 33 and 34 mounted in carriage II. The upper ends of the shafts may be supported by brackets 30 and 3I mounted on slides 33 and 34, respectively, and the rolls may be carried on bearings such as those illustrated at 35 and 36. Both slides are supported by shoulders 31 and 38 in the carriage and are retained in position by gibs 31a and 38d. The slide 33 supporting roll I2 may be moved along the shoulders 31 and 38 by rotation of the screws 40 which are in threaded engagement therewith as shown in Figures 2 and 5. The screws 40 pass through openings in a bracket 4I supported by the carriage II, and endwise movement of the screws with respe-ct to the carriage is prevented by the nuts 43 and 44 mounted on the screws 40 together with their asso'ciated bearing washers 45 and 46. At their ends the screws 40 are provided with worm wheels 41 which are engaged by worms 48 mounted on shaft 49 which is suitably supported in brackets 50. Thus rotation of the shaft 49 will result in simultaneous rotation of the screws 40 and corresponding movement of the slide 33 and pressure roll may be indicated by the pointer 5I and the dial 52, the pointer being carried by shaft 49 while the dial is mounted on the bracket 50.

The pressure roll I4 is also moved, in a direction opposite to the movement of roll I2, by the screws 40 which extend through but do not engage slide 34, and'project beyond the opposite end of the carriage I I. The yoke 53 is in threaded engagement with the projecting ends of the' screws 40 which are provided with threads 54 of opposite hand to those engaging slide 33. Thus rotation of the screws 40'by means of the shaft 49 will cause the yoke 53 to be moved in a direction opposite to the direction of movement of the slide 33. That is, rotationiof shaft 49 in one direction will cause slide 33 and yoke 53- to apslide 34 through the pressure responsive devicev I5 which is mounted on slide 34 by the cup shaped member 55 (see Figure 3) and which is engaged by the end of screw 56 mounted on` yoke 53. To maintain Constant engagement'between the pressure responsive device I5, the yoke 53 and the slide 34, springs 51 acting between ears 56 formed on the yoke 53 and washers or' stops 59 carried by the rods 60 are employed. The rods 60 are mounted on the slide 34 so that the springs 51 constantly urge the slide toward the yoke. The forces exerted by the springs are small in comparison to the pressures of the welding rolls against* the tube and for most purposes can be disregarded. Thus the forces transmitted between slide 34 and yoke 53 through the pressure The position of the adjusting mechanism .40

responsive device I5 are'substantially equal to the pressure exerted by rolls I2 and I4 on the.

tube A. By means to'be described in detail below, the forces to which'device I5 is subjected are indicated on gage I1, which thus furnishes a continuous indication of the pressures between rolls I2 and I4 and the tube.

In order to measure'the pressures exerted by the electrode rolls I 9 and 20 upon the tube A carriage II is mounted for limited rotational movement with respect to the base I0. As shown particularly in Figures 2, 4 and 5 the pivotal mounting may comprise hinge shaft 65 supported from the base I0 by brackets 66 and engaged by members 61 mounted along one end of the carriage II. The carriage is supported at its opposite end by an adjusting screw 68 which rests upon the upper surface of the pressure responsive device 25 which is supported on the bracket 69 mounted within the base I0. Preferably the device 25 is adjustably supportedion the bracket 69 by the jack screw 10. Preferably the pivotal movement of the carriage with relation to the base III is limited by the slotted member 1I which is bolted to the frame I0 and receives the lug 12 formed on the carriage II. The dimensions of the lug 12 are-slightly smaller than the dimensions of the slot or groove in the member 1I so that a slight rocking movement of the carriage about the rod 65 is permitted.

By this construction the pressure exerted by screw 68 on the pressure responsive device 25 is a function of the pressure exerted on the tube by the electrodes I0 and I2. In the embodiment shown the leverage is such that, after allowance has been made for that portion of the weight of the carriage which is supported by pressure responsive device' 25, the pressures' exerted on the device 25 are equal to about one-half thevpressures exerted by the ,electrode roll. Thus by properly calibrating the pressure responsive device 25 and its associated mechanism the gage 21 will accurately indicate the pressures exerted on the tube by the electrodes I0 and I2.

The pressure responsive devices I5 and 25 may be Constructed in any convenient manner. For example, if desired, an hydraulic bellows or cylinder might be employed in which case ordinary pressure gages could be employed to indicate the welding pressures. However, I preferablyemploy the device shown in Figuresfi and 7 in'conjunction with the electrical apparatus diagrammatically illustrated in Figure 8 in order to obtain an accurate' and a simple' pressure indicating device iniwhich the variations in pressure can be indicated-with very small movements of theflparts. A preferred form of such device comprises la housing 15 having a closed bottom wall 16 and a cylindrical side wall 11. The open end -of the housing is closed by a diaphragmv 16 Secured to the wall 11 as by screws 19 and having a rounded central projection 60. As installed to measure thev pressure of the welding rolls, -the housing 15 of device I5 is Secured to' the slide 34 while the hollow-pointed screw 56 on yoke 53 engages the projection on diaphragm 18. 4 Similarly the base or bottom wall 16 of pressure. responsive device 25 is supported from bracket 69 by jack screw 10, while projection 80 is engaged by screw 66 projecting downwardly from the-carnage II. Thus in both instances the forces transmitted through the diaphragms 18 vary with the pressures, and therefore the deflections of the' diaphragms will be functions of the pressures applied.

To measure the deflections and thus to determine the pressures, I preferably employa coil BI supported within the housing from the diaphragm 18 by a threaded rod 82 while a similar coil 83 is supported from the bottom wall 16 of the housing by a screw 84 which is engagecl b'y nut 85 supported by suitable bearings carried by the blocks BG. The nut 85 is formed integrally with a wormwheel Bl engaged by a Worm 88 mounted on shaft 89 which projects through the side wall 11 of the housing and is provided at its end with the knob 90 whereby the rod can be rotated to raise and lower the coil 83 to thus adjust its position with respect to the coil 8I. Leads from the coils 8! and 83 are carried to the exterior of the housing through nipple 9! threaded into the side wall l'l.

It will be evident that variations in the loacls applied on the diaphragm 80 will cause variations in the defiection of the diaphragm and will result in relative movement between the coils hl and 83. It is this relative movement which employ to give an indication of the pressures exerted by the welding rolls and the electrodes, through the -preferred form of electrical circuits illustrated in Figure 8.

As shown in Figure 8 the coils Si and 83 are connected in series with the common terminals of the coils grounded. Therefore the impedance of the circuit including the coils will be changed by variations in the distance between the coils caused by defiections of the diaphragm l under load. To supply a high frequency alternating current to this circuit and to measure and indicate the resulting changes in the current due to changes in the distance between the coils I preferably employ a vacuum tube circuit of the type illustrated. This comprises a power supply unit including the transformer Hill, having its primary connected to a 110 volt alternating current supply and having secondary windings adapted to produce the various filarnent and plate voltages for energizing the several vacuum tubes, the rectifier tube m2 and the voltage regulator tube m3 which, in conjunction with the circuits shown, function to maintain the output voltages of the power unit substantially Constant regardless of fiuctuations in the load or fluctuations in the alternating current supply voltage. The circuit also includes the oscillator tube Mill shown herein as a tube of the -triadyne type which generates a high frequency alternating current supplied to the coils Bl and 83.

The strength of the high frequency current generated by tube llll is varied by the relative position of coils 8! and 83. Thus the output of tube Hill varies in accordance with the load on the diaphragm 78 of the pressure indicating device. The output of tube m4 as'controlled by the position of coils ti and 83 is fed to the control grid of amplifier tube m5 which in turn operates ,voltmeter mt. Thus by the Connections shown the voltmeter will indicate variations in the dis- In the welding apparatus shown two pressure responsive devices i and 25 are utilized as previously described. Separate electrical circuits and voltmeters are employed, the voltmeters lll for devices lil and 25 constituting gages il and 21, respectively, as shown in Figure l. Each pressure indicator may be readily calibrated by setting up its pressure responsive unit in a compressiontesting machine. Then withv no load on the unit the voltmeter or gage il or 'l, as the case may be, is brought to a desired Zero reading by rotating the knob 98 to adjust the distance between the coils lil and 83 to bring the needle of the voltmeter to some arbitrarily selected point, preferably near the center of the scale. The position of knob 98 is noted, then ncrements of load are applied to the diaphragm ltl by the testing machine and the voltmeter again brought to the same point by turning the lrnob l'lil, the number and direction of the turns required to bring the voltmeter to the established point being recorded for each increment. This furnishes data for calibration of the relationship between the load on the diaphragm and the 5 various settings of knob 98 giving a. Constant reading of meter m6. vFor each position of knob to selected, the apparatus is calibrated for smaller load increments until the meter reading is Zero and then increasing the load until the meter reads full scale, noting the rneter readings corresponcling to various loads within this range. This procedure may be carried out for all of the various positions of the selector switch lllE) so that the instrument will be calibrated for a wide range of loads.

After calibration the pressure responsive devices are placed as described in the v/elding :machine, the no-load calibration of both instruments is checled, a tube A is run between the welding rolls and beneath the electrodes, and then the knobs iii of both devices are adjusted to bring the needles of meters l'l and Zl, back to their arbitrarily selected Zero positions, whereupon the pressures on the tube can be determined frorn the positions of the knobs Eiti of each pressures ernployed, and by ineans of the adiusttance between the coils 84 and 88 and since these variations are caused by defiections of the ments for the electrodes and the welding rolls,

the operator' of the machine can maintain the Welding pressures at the correct values, and can quiclrly adjust the machine to the welding pressures desired.

From the foregoing description of a preferred form of my invention it will be evident that .l have provided a welding apparatus in which the welding pressures applied to the tube at the welding throat are accurately indicated and in which the pressures may be readily adjusted to their correct values. Myapparatus gives a Constant and instantaneous indication of the welding pressures exerted by the welding rolls as Iwell as by the electrodes. By my invention it is now possible to control accurately all of the important factors deterrnining the character of the weld produced by a tube welding machine, name- 1y;speed of the tube, weldin'g current, and the pressures applied at the welding throat. My pressure responsive devices are sturdy and efficient and accurately indicate the welng pressure-s, and because the devices indicate pressures with only very minute movements of the parts, they do not change the normal Operation of the machine except to make it possible for the operator to maintain correct pressures at all times.

In the foregoing specification I have described a preferred form of my invention as applied to one particular type of tube welding machine. It will be evident to those skilled in the art that the invention can be adapted to other types of welding machines, and that various changes and modifications can be made in my apparatus without departing from the teachings of my invention. Therefore it is to be understood that my patent is not limited to the preferred form described herein or in any manner other than by the scope of the appended claims.

I claim:

1. In a welding machine a frame, a carriage pivotally mounted on said frame, welding rolls supported by said carriage and adapted to engage opposite sides of a tube passing through said machine, electrode rolls adjustably supported by said frame and engaging said tube in the region adjacent said welding rolls, the pressure between said electrode rolls and said tube urging said tube into engagement with said welding rolls and tending to rotate said carriage about its pivotal mounting on said framaand. pressure responsive means interposed between said carriage and said frame for supporting said carriage against rotation and indicating the pressure exerted by said electrode rolls on said tube. 2. In a welding machine, a frame, a carriage mounted on the frame, slides mounted on said carriage, welding rolls carried by said slides and adapted to be moved toward and away-from each other and into engagement with a tube blank passing through said machine, andmeans for urging said slides and said welding rolls toward each other comprising a screw in threaded engagement with one of said slides and extending through the other of said slides, a yoke in threaded engagement with a portion of said screw projecting beyond said second slide, the threads on said screw being arranged so that rotation of said screw causes said yoke and said first slide to `be moved in opposite directions, and a pressure responsive device interposed between said yoke and said second slide for transmitting the movement of said yoke to said second slide and for urging said second slide toward the said first slide.

3. In a welding machine a frame, a carriage pivotally mounted on the frame, welding rolls mounted on said carriage and adapted to engage opposite sides of a tube blank passing through said machine, means for urging said rolls toward each other and into engagement with said blank including a pressure responsive device for indicating the pressures between said welding rolls and said blank, electrode rolls adjustably supported by said frame and adapted to engage the upper surfaces of said blank and pressure responsive means interposed between said carriage and said frame for at least partly supporting said carriage and indicating the pressure exerted by saidelectrode rolls against said blank.

4. In. a continuous tube welding machine the combination of opposed welding rolls, means to propel a tube blank axially between and in contact with said rolls, a fixed member, means carrying at least one of said welding rolls and movable toward and away from said fixed member, electrode rolls engagcable with and applying pressure to said blank tending to move said movable member relative to said fixed member, and meansfor indicating the pressure so applied, and serving to transmit said pressure from said movable member to said xed member.

5. In a continuous tube welding machine the combination of opposed welding rolls movable relative .to each other, means to propel a tube blank axially between and in contact with said rolls, a frame, supporting means carrying said welding rolls and pivotally movable toward and away from said frame, electrode rolls engageable with the tube blank adjacent to said welding rolls, said electrode rolls exerting pressure on said blank and welding rolls tending to move said welding rolls apart and said pivoted member toward said frame, pressure indicating means serving to transmit from one of said welding rolls to the other the pressure which tends to move said welding rolls apart and pressure indicating means serving to transmit to said frame the pressure which tends to move said pivoted means towardsaid frame.

6. In a continuous tube welding machine the combination of a fixable member carrying a welding roll, a member slidable relative to said fixable member and carrying a second welding roll, means to propel a tube blank axially between and in contact with said welding rolls, electrode rolls engageable With and applying pressure to said blank tending to move said slidable member. relative to said fixed member, and means indicating the pressure applied to said movable member and serving to transmit said pressure from said movable member to said fixed member.

7. In a continuous tube welding machine the combination of a fixed member, a pivoted member carrying opposed welding rolls and capable of limited movement-toward and away from said fixed member, means to propel a tube blank axially between and in contact with said welding rolls, means including electrode rolls for applying pressure to the tube and thence through the welding rolls to said pivoted member tending to move the pivotal member towards said fixed member, and means indicating the pressure so applied and serving to transmit said pressure from said pivoted member to said xed member.

8. In a continuous tube welding machine, the combination of a frame, sets of welding rolls and electrode rolls operatively connected to said frame and constituting a welding throat, one of said sets of rolls being capable of limited movement relative to said frame, means to propel axially through said welding throat a tube blank with coincident creation of pressures tending to move said movable set of rolls relative to said frame, and means for indicating such pressures and servingto transmit them from said movable set of rolls to said frame.

FREDERIC M. DARNER. 

